The \( \Delta_f H^\theta \) of \( AO_3(s) \), \( BO_2(s) \), and \( ABO_3(s) \) is -635, \( x \), and -1210 kJ mol\(^{-1}\) respectively. The reaction:
\( ABO_3 (s) \rightarrow AO_3 (s) + BO_2 (g) \)
Has an enthalpy change of \( \Delta_r H^\theta = 175 \) kJ mol\(^{-1}\). What is the value of \( x \) (in kJ mol\(^{-1}\))?
